U.S. Pat. No. 4,367,963 issued to Daughters for a "Refillable Typewriter Ribbon Cartridge" discloses a ribbon cartridge designed to meet a set of problems in the typewriter art that are completely different from the more precise video tape cassette art. The top 40 and bottom 42 of the Daughters device are joined by hinged side 44.
In U.S. Pat. No. 4,227,622, video tape cassettes are disclosed in which the mounting of upper and lower halves to each other is carried out through fastening means. However, the screwing of the two halves is a time consuming operation in production and requiring a heavy plastic. The U.S. Pat. Nos. to Dobbs et al 4,249,710 and Wardenaar et al 4,235,395 both disclose magnetic tape cassettes wherein the cassette housing has its upper and lower portions hingedly connected to one another.
Oishi U.S. Pat. No. 4,341,365 discloses a miniaturized video tape cassette such as for a portable video system which avoids hubs with flanges normally utilized in conventional full-size video tape cassettes, by using flangeless tape winding hubs each being composed of an inner drum loosely fitted within an outer drum with torque transmitted between the drums by arms extending from the inner drum and fitting into corresponding slots in the outer drum. In addition, teeth are provided in the hub and cassette which engage to hold the tape stationary when the cassette is not in use. This cassette also uses springs which bias the hubs toward the engaged position except when the cassette is loaded into a video tape machine which causes the hubs to be lifted away from the teeth of the cassette.
The Umeda U.S. Pat. No. 4,559,574 also discloses a miniature type cassette which is capable of use in different types of equipment, and in which the cassette casing may be formed of polypropylene. This device includes a supply reel having teeth on the lower surface of its lower flange, these being capable of engaging with complimentary teeth in the cassette bottom wall.
As the video tape travels through the cassette between the two spools, it conventionally passes about one or more guide posts, e.g. the post 7 of the Ito et al U.S. Pat. No. 3,645,462 and the posts 7 and 8 of the Shiba U.S. Pat. No. 4,382,565. Also see the guide post in the cartridge of the Collins et al U.S. Pat. No. 4,561,609 and those in the Gelardi et al U.S. Pat. No. 5,092,536. These guide posts are conventionally rigid posts, although there is one prior art construction which utilizes a combination of rigid posts and rotatable sleeves, the rotatable sleeves being used on the interior of the device and rigid posts being used on the outside of the cassette but inside of the dust cover. The rigid posts, against which the tape runs as it plays, rub against the tape causing a number of negative results, including scratching and stretching of the tape, these in turn causing distortions. In addition, the rigid posts tend to wear out the tape more quickly.
The Gelardi et al U.S. Pat. No. 5,092,536 discloses an integrally molded cassette including not only top and bottom portions, but also an integral dust cover, and wherein the top and bottom portions are ultrasonically welded together. An external dust door latch or latch flap is shown for maintaining the dust cover in normally closed position. However, even though such latch flap is internally located relative to the dust cover, it is externally located relative to the cassette casing itself, and thus subject to becoming damaged as the dust cover opens and closes each time the video cassette is engaged within a player/recorder. Moreover, the simplest embodiments of the Gelardi patent rely on the integral hinges themselves to provide sufficient spring force, but in practice the spring force provided by the hinges is insufficient and additional metal springs such as illustrated in FIG. 40 of the Gelardi patent must be used. In the commercial embodiment of the Gelardi device, the latch flap 67 (FIGS. 8, 50 and 51) is not used, but instead only a metal spring is used to bias the dust cover closed, but such dust cover can be undesirably easily opened so that the video tape becomes damaged.
Other patents describing the closest subject matter provide for a number of more or less complicated features that fail to solve the problem in an efficient and economical way. All of the above-noted prior devices suffer from one or more of a number of disadvantages, primarily in the area of being unable to perform all necessary functions in the desired manner without the provision of unduly costly and complex means. The video tape also wears out too quickly in these prior devices. None of these prior patents suggest the novel features of the present invention. Thus, the need continues to exist for a fully effective and less costly video cassette with a minimum number of pieces, and which is formed entirely of plastic and without the need for additional non-integral elements such as springs of metal or plastic.